#Diphtheria

Parajuli SB, 2026 (www.suryaparajuli.com.np)

For Community Medicine (Kathmandu University) | MBBS 3rd Semester |
Birat Medical College Teaching Hospital

#🔹 Specific Learning Outcomes (SLOs)

At the end of the session, the learner will be able to

• Describe the problem statement and public health importance of Diphtheria globally and in developing countries.

• Explain the epidemiological determinants of diphtheria including agent, host, and environmental factors.

• Identify the clinical features and complications of diphtheria including respiratory and cutaneous forms.

• Discuss the prevention and control measures including case management, contact tracing, and isolation.

• Describe the immunization strategies including types of vaccines, schedule, and importance of booster doses.

#🦠 Problem Statement – Diphtheria

🌍 Rare in developed countries due to routine childhood vaccination 💉

📉 Declined significantly where strong immunization programs exist

⚠️ Still occurs in non-immunized children in developed countries

🔄 Changing epidemiology due to:

• Decreasing immunization coverage

• Waning immunity in adults

• Irregular vaccine supply

• Population movement

👥 Shift in cases toward older children & adults

🌐 Endemic in developing countries due to low vaccination coverage

📉 Underreporting common → true burden unknown

📊 ~8,639 cases reported globally in 2021

#🦠 Definition (Diphtheria)

Acute bacterial infectious disease caused by toxigenic strains of Corynebacterium diphtheriae.

🔴 Local effects:

• Congestion

• Oedema

• Tissue destruction

🟢 Lymph nodes:

• Regional enlargement

⚠️ Systemic effects:

• Toxaemia (toxin in blood)

📊 Fatality rate:

• 5–10% (untreated)

• Higher risk: <5 yrs & >40 yrs

• Severe cases: up to 20%

🧍‍♂️ Sites affected:

• Throat (faucial, laryngeal)

• Also: nose, skin, conjunctiva, vulva

⚙️ Pathogenesis:

• Local multiplication (usually throat)

• Production of powerful exotoxin

🧫 False membrane:

• Greyish/yellowish patch on tonsils/pharynx/larynx

• Firm, cannot be wiped off

#Nepal Situation – Diphtheria

📍 Diphtheria is not fully eliminated; sporadic cases still occur

💉 Routine immunization (DPT/ pentavalent vaccine) has reduced cases significantly

⚠️ Cases mainly seen in:

• Unvaccinated or partially vaccinated children

• Remote or underserved areas

🔄 Risk factors in Nepal:

• Gaps in immunization coverage

• Migration and cross-border movement

• Limited booster dose uptake

👥 Occasional outbreaks reported in clusters, including older children/adults (due to waning immunity)

📊 Recent trend:

• Low number of reported cases, but underreporting possible

#India Situation

📍 Endemic disease

📉 Declining trend due to improved immunization

📊 Cases reported in 2022 (approx.):

• Telangana: 1,441 cases

• Rajasthan: 182 cases

• Gujarat: 56 cases

⚠️ Most cases linked to immunization gaps

#🦠 Epidemiological Determinants

#Agent Factors

🔬 Agent:
Corynebacterium diphtheriae

• Gram-positive, non-motile

• Non-invasive but produces powerful exotoxin

🧪 Types:

• Gravis

• Mitis

• Belfanti

• Intermedius

Gravis → more severe disease

⚠️ Toxigenicity:

• Not all strains are toxigenic

• Can become toxigenic via beta bacteriophage

❤️ Toxin effects:

• Heart → myocarditis

• Nerves → paralysis

💊 Sensitivity:

• Sensitive to penicillin

• Killed by heat & disinfectants

• Survives briefly in dust & fomites

#Source of Infection

• Cases (clinical & subclinical)

• Carriers (temporary or chronic)

• Nasal carriers → more infectious

🧫 Infective material:

• Nasopharyngeal secretions

• Skin lesion discharge

• Fomites & dust

⏳ Period of infectivity:

• 14–28 days (untreated cases)

• Carriers may remain infective longer

• Non-infective after 2 negative cultures (nose & throat)

#Host Factors

🎯 Age:

• Mainly affects children 1–5 years

• With immunization → shift to older children (school age)

⚧️ Sex:

• Both males and females affected equally

🛡️ Immunity:

• Infants have temporary protection from maternal antibodies

• Natural immunity previously developed via inapparent infection

• By 6–8 years, ~75% children have protective antitoxin (in endemic areas)

#Environmental Factors

📅 Occurs in all seasons

❄️ Higher incidence in winter months (favours spread)

#🔄 Mode of Transmission

💧 Mainly spread by droplet infection

🤲 Direct contact with infected skin lesions

🧸 Indirect spread via contaminated objects (short survival):

• Cups

• Toys

• Thermometers

• Pencils

#🚪 Portal of Entry

🌬️ Respiratory tract (most common)

🩹 Non-respiratory routes:

• Skin (cuts, wounds, ulcers)

• Umbilicus in newborn

• Eye, genitalia, middle ear (rare)

#⏳ Incubation Period

📅 2–6 days

⏱️ Sometimes longer

#🩺 Clinical Features – Diphtheria

#🌬️ Respiratory Forms

Types:

• pharyngotonsillar

• laryngotracheal

• nasal

#🧑‍⚕️ Pharyngotonsillar Diphtheria

• Sore throat

• Difficulty swallowing

• Low-grade fever

Throat findings:

• Mild redness

• Exudate

• Pseudomembrane

Membrane characteristics:

• White → blue-grey/black

• Firm

• Adherent

• Bleeds on removal

Severe sign:
“bull neck” appearance
(neck swelling + lymphadenopathy)

#😮‍💨 Laryngotracheal Diphtheria

• Fever

• Hoarseness

• Croupy cough

Airway obstruction →

• Dyspnea

• Prostration

May mimic:

• Viral croup

• Epiglottitis

Severe cases →

• Suffocation if untreated

• Needs airway support

#⚠️ Toxic Effects

Exotoxin spread → damage to:

• Heart → arrhythmia, myocarditis

• Liver, kidneys, adrenals

• Nerves → paralysis (palate, eye muscles, limbs)

#👃 Nasal Diphtheria

• Mild form

• Usually unilateral nasal involvement

• May extend to pharynx

#👁️‍🗨️ Other Sites

• Conjunctiva

• Genital mucosa

#🩹 Cutaneous Diphtheria

• Common in tropical areas

• Secondary infection of skin wounds/abrasions

• Chronic ulcer with membrane + surrounding redness

#🛡️ Control of Diphtheria

#👥 1. Cases & Carriers

🔍 Early detection:

• Active search in family & school contacts

• Nose + throat swab culture required

• Check organism virulence

🚫 Isolation:

• All cases, suspected cases & carriers

• Hospital isolation for ≥14 days

• Release only after 2 negative swabs (24 hrs apart)

💊 Treatment (Cases):

• Immediate diphtheria antitoxin (dose depends on severity)

• Antibiotics: penicillin / erythromycin (5–6 days)

💊 Treatment (Carriers):

• Oral erythromycin for 10 days

• Update immunization status

#👨‍👩‍👧 2. Contacts

🧪 Throat swab + immunity check

📌 Management based on immunization status:

💉 Immunized <5 years → no action

💉 Immunized >5 years → booster dose

❌ Non-immunized → antibiotics + antitoxin + active immunization

👀 Surveillance:

• Daily monitoring for ≥1 week

• Repeated swab testing for several weeks

#🌍 3. Community Control

💉 Primary strategy:
vaccination with diphtheria toxoid

👶 Early infant immunization + booster every 10 years

⚠️ Goal:
Maintain protection before maternal immunity wanes

📊 High coverage needed
(vaccination does NOT prevent carrier state)

#💉 Diphtheria Immunization

#Current Prophylactics

🔗 Combined / Mixed Vaccines

• DPT vaccine

• DTPw (whole-cell pertussis)

• DTPa (acellular pertussis)

• DT (diphtheria + tetanus)

• dT (adult type)

• Pentavalent (DPT + Hep B + Hib)

#💉 Single Vaccines

• FT (formol toxoid)

• APT (alum-precipitated toxoid)

• PTAP (aluminium phosphate toxoid)

• PTAH (aluminium hydroxide toxoid)

• TAF (toxoid-antitoxin flocculus)

#🧴 Antisera

Diphtheria antitoxin

#👶 Pentavalent Vaccine (EPI)

🛡️ Protects against 5 diseases:

• Diphtheria

• Pertussis

• Tetanus

• Hepatitis B

• Hib

💉 Given at:
6, 10, 14 weeks

📉 Reduces number of injections

💉 Administration:

• IM injection (anterolateral thigh)

• Dose: 0.5 ml

❄️ Storage:

• 2–8°C

• Freeze-sensitive

⚠️ Side Effects:

Common:

• Pain

• Redness

• Fever

• Irritability

Rare:

• High fever

• Seizures

• Allergic reaction

#💉 Single Vaccines

Examples:

• FT

• PTAP

• APT

• PTAH

Used less frequently

All are effective immunizing agents

Each dose contains
~25 Lf units of diphtheria toxoid

⚠️ APT rarely used → higher risk of reactions

#🧴 Antisera

Diphtheria antitoxin (horse serum)

Used for:

• Passive prophylaxis

• Treatment

#📚 References

• WHO (2021) – Diphtheria: Reported cases by WHO region

• WHO (2017) – Weekly Epidemiological Record, No. 31, 4 Aug 2017

• WHO (1999) – Health Situation in the South-East Asia Region (1994–1997), Regional Office for SEAR, New Delhi

• WHO (1996) – World Health Report: Fighting Disease, Fostering Development

• WHO (1995) – World Health Report: Bridging the Gaps

• Youmans, G.P. et al. (1980) – The Biological and Clinical Basis of Infectious Diseases, 2nd ed., Saunders

• Govt. of India (2023) – National Health Profile 2023, DGHS, Ministry of Health & Family Welfare, New Delhi

• CDC – Factsheet for Parents, reviewed Feb 2013

• Jawetz et al. (2013) – Medical Microbiology, 26th ed., Lange Medical Book

• Lawrence, M. et al. (2008) – Current Medical Diagnosis and Treatment, 47th ed.

• Downham, M.A.P.S. (1976) – British Medical Journal, 1:1063

• WHO (1985) – Bulletin of WHO, 63(6):1151–1169

• CDC (2019) – Epidemiology and Prevention of Vaccine-Preventable Diseases

• Edsall, G. (1975) – Clinical Aspects of Immunology, Blackwell, Oxford